I want to control my electric baseboard heaters all at once (through web interface or else). I found that Sinope might be the best option so far but the new model that just came out sells for 110$ each. Since i need 10 of them, that pretty expensive.
Use smartthings with a smart plug (if wattage low enough) and one of the integrated temp sensors
That way you can program them to turn on/off when you want and use a smartapp to control room temp.
Just for the price of 10x smartplugs or similar and a smart sensor of some kind
It depends on where you are as to that answer.
There a big differences in the devices you can buy depending on your hub and where you are.
I live in the UK so my choices are more limited than someone living in the US